El objetivo de este trabajo fue analizar el efecto de la sal sobre algunas propiedades físicas del queso, su interacción con los componentes del queso, y el efecto del contenido de sodio sobre la salud de los consumidores. La sal es un ingrediente importante, ya que determina en gran parte la calidad del producto y la aceptación del consumidor. El salado del queso tiene in uencia en la calidad debido a sus efectos sobre la composición, el crecimiento microbiano y la actividad enzimática. Ejerce una in uencia signi cativa sobre la reología y textura, así como en la maduración, principalmente a través de sus efectos sobre la actividad del agua. Los niveles de sal en queso van desde aproximadamente 0,6% p/p hasta aproximadamente 7% p/p. Debido a que el consumo de queso está aumentando en todo el mundo, se debe dar importancia a la reducción de la sal sin afectar su consumo. Entre las estrategias que se han planteado con tal n está la sustitución parcial de la sal por otros compuestos. Pero el inconveniente de la sustitución del NaCl es su efecto sobre las propiedades sensoriales, la composición química, la proteólisis y la textura del queso. Otra interesante alternativa para el reemplazo del NaCl, es el uso de la tecnología de membranas para obtener permeado rico en sales provenientes del lactosuero; la adición de estas sales en la elaboración quesera, produce quesos bajos en sodio, con buena textura.
The correlation of two instrumental techniques for chlorides determination in Colombian cheese, Queso Molido Nariñense (a type of white cheese), was analyzed. Potentiometry of chloride precipitation is the standard technique to determined salt in cheese. Conductimetry is an alternative technique. Samples of Queso Molido Nariñense were made. In the processed cheeses the salt concentration (NaCl: 0.5 %, 0.8 %, 1.0 %, 2.0 %, 3.0% and 6.0 %) was varied. Chlorides were determined by titration with silver nitrate in the potentiometric technique. In the conductimetric technique, each sample was analyzed by direct measuring its conductivity at room temperature. It was found that there is an adequate correlation between potentiometry and conductimetry. A maximum concentration of 2% NaCl in cheese is equivalent to 2.9 S/cm for conductivity readings. Additionally, it was verified that the conductimetry constitutes an analytically reliable technique for the determination of chlorides in cheese, it is friendlier to the environment, cheaper and faster.
A voltammetric method optimized for the sensitive and reliable study of the UV/H2O2 oxidation of glyphosate (N- (phosphonomethyl) glycine) (GPS). The cell consisted of three electrodes in a compartment, silver wire coated with silver chloride as a pseudo reference electrode, platinum electrode as working electrode and stainless steel as auxiliary electrode. GPS cyclic voltammetric analysis suggests the formation of a GPS-Pt complex on the electrode surface, with an enhanced signal in perchloric acid between 1.3 to -1.3V; sensitive to protonation of the amino group, no response observed at pH values greater than 5.00. The oxidative degradation of GPS with UV/H2O2 is evident at pH 3.0, it exhibits first order pseudo kinetics with a half-life of 40 ± 4min. Two degradative routes are estimated depending on the concentration of H2O2: at low concentrations (H2O2/GPS 1: 100 ratio), the formation of sarcosine and then glycine is favored; at H2O2/GPS 1:20 and 1:10 ratios predominate the formation of glycine.
A sensory study was conducted at the Universidad Santiago de Cali with Queso Molido Nariñense. To determine the preferred levels of concentration acceptable by consumers, samples were made with different concentrations of NaCl (C1 = 0.62%, C2 = 0.87%, C3 = 1.05%, C4 = 1.74%, C5 = 2.71%, and C6 = 5.34%). The results show that sample C4 had the highest degree of acceptance, followed by C2, C3, and C5, while C1 and C6 had the lowest acceptance. Consumers were able to distinguish salt differences above 0.27%. It was possible to predict consumer reaction regarding their levels of acceptability and perception using the Sensory-Instrumental correlation. This result showed that either an extremely low or a very high level of concentration of salt in cheese could result in a low acceptance by consumers.
In this study, the electrochemical behavior of diclofenac (DCF), a widely used NSAID drug, was undertaken at a modified glassy carbon electrode (GCE). A low-cost, sensitive, stable, and selective electrochemical sensor is proposed for the determination of this analyte by using differential pulse voltammetry in 0.10 M phosphate buffer solution, pH 8.00. At the Surface of GCE, EDOT (3,4-Ethylenedioxythiophene) was electropolymerized by chronocoulometry, the charge injected was carefully controlled. The polymerization parameters were 20.0 mM EDOT, H2SO4 pH 1.50, step potential from 0.0 V to 1.1 V vs Ag/AgCl/KCl(sat), for 60 ms. The modified GCE displayed a significant enhancement of the anodic peak current compared to the bare electrode, measured by DPV. A calibration graph of the modified electrode exhibited an increase of the peak current about 63% with respect to the bare. The electropolymerized sensor was applied to DCF quantitation in pharmaceutical preparations with a relative standard deviation of 0.40%. It was also used in urine analysis. The limit of detection of this sensor was 9.06 nM compared to 1.37 μM for the bare electrode.
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